A. Field of the Invention
The present invention relates to control systems for manipulator apparatus and more particularly to an improved control system for manipulator apparatus utilizing servoloops that provide improved dynamic performance and initializing stabilization of the manipulator arm in a plurality of controlled axes by the use of variable inertia scaling and initializing of command signals via force and inertia correlated feedback from the actuators of predetermined axes.
B. Description of the Prior Art
Various control systems for manipulator apparatus have been proposed and/or implemented utilizing servo-loops having command signals and feedback signals to position a manipulator arm controlled by a plurality of axes.
Control systems of this type, for example, are disclosed in U.S. Pat. Nos: 4,362,978; 3,661,051; 4,086,522; 4,132,937; 4,338,672; 4,156,835 and 4,243,923. The control system of U.S. Pat. No. 4,362,978 provides a torque/force command loop utilizing force or pressure feedback and inertia scaling of various command signals. The inertia scaling is accomplished either by look up table or on-line computation utilizing load weight and arm position as parameters. The control system of U.S. Pat. No. 3,661,051 utilizes a servoloop having position command signals and position feedback signals to control the manipulator arm. U.S. Pat. No. 4,086,522 utilizes position and velocity command signals, and position and velocity feedback in a servo control loop. U.S. Pat. No. 4,132,937 utilizes dynamic feedback including acceleration feedback and velocity feedback data that is combined with the position error signal to stabilize the control and operation of the manipulator arm by providing a high negative dynamic feedback signal during deceleration and a low signal during the acceleration phase to avoid conflict between the positional error signal and the dynamic feedback signal. U.S. Pat. No. 4,086,522 utilizes a servo-loop having position, velocity and acceleration command signals and position, velocity and acceleration feedback for control of the manipulator arm.
While the above prior art arrangements have, in general, been found satisfactory for their intended purpose, there is a continuing need in many manipulator applications for improved initializing stabilization and dynamic performance while maintaining servo-loop stability. Further, there is a need for improved dynamic performance of manipulator arm control where the manipulator arm experiences a wide variation in arm loads during performance of a work task.